Packaging machine and method



1962 R. A. MAHAFFY 3,

PACKAGING MACHINE AND METHOD Fig.l

- INVENTOR. Reid A. Muhuffy 1962 R. A. MAHAFFY 3,061,984

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PACKAGING MACHINE AND METHOD Filed Sept. 25, 1959 9 Sheets-Sheet 3 Q 0 o m w g 2 8 I QL AT TORNEYS Nov. 6, 1962 R. A. MAHAFFY 3,061,934

' PACKAGING MACHINE AND METHOD Filed Sept. 25, 1959 9 Sheets-Sheet 4 INVENTOR. Reid A.Mohoffy BY @0655 Man/vi 1 M d A T TO RN E YS Nov. 6, 1962 R. A. MAHAFFY 3,061,984

PACKAGING MACHINE AND METHOD Filed Sept. 25, 1959 9 Sheets-Sheet 5 I07 F lg 19 5, I07

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0 m m g United States Patent Ofifice 3,061,984 Patented Nov. 6, 1962 3,061,984 PACKAGING MACHINE AND METHOD Reid A. Mahaffy, 105 Clinton Ave., Montclair, NJ. Filed Sept. 25, 1959, Ser. No. 842,365 33 Claims. (CI. 5322) This invention relates to packaging apparatus and a method of forming sealed packages. More in particular, this invention relates to method and apparatus for automatically forming a package from sheets of packaging material, evacuating the package, and sealing it to prevent entry of oxygen and the like.

Since the development of heat-scalable flexible packaging materials with a low rate of gas permeability, particularly with respect to oxygen, evacuated food packages made from such materials have found wide acceptance because of their extended shelf life as compared to conventional packages. Sliced luncheon meats, bacon, frankfurters, sliced dried beef, cheeses, nuts and dried fruits have particularly benefited from such packaging since protection from atmospheric oxygen materially lengthens their shelf life. Where the atmospheric pressure surrounding a vacuum package would cause mechanical damage to the packaged product or to its container, an inert gas such as nitrogen or a gas with other beneficial properties such as carbon dioxide is often introduced into the package after evacuation to reduce or eliminate the pressure differential to which the package walls would otherwise be subjected.

Originally, the articles to be packed were inserted into pouches of the heat-scalable material, and the pounches were then evacuated and sealed by equipment especially designed for this purpose. Subsequently, equipment was developed to automatically produce complete vacuum or gas packages, starting with container material in rolls of continuous sheets rather than with pouches, for the purpose of effecting economies in packaging materials and labor. In such vacuum and gas packaging equipment, it is desirable to assure wrinkle-free sealing areas since, on a statistical basis, wrinkles in the package seals may be a major factor in package leakage prior to expiration of the period of normal package life expectancy, particularly when the packaging materials are nonhomogeneous or laminar in structure. The latter materials generally are used because they have so far proven to be more suitable for such packaging than homogeneous materials when economic and functional considerations are taken into account.

In producing such packages automatically, it is advantageous to seal as much of the package as possible before the evacuating and/or gassing operations, leaving an aperture for evacuating and subsequent gassing. This preliminary sealing operation is easier to complete in a wrinkle-free manner than the final sealing operation since the fluid flow occurring during evacuation or gassing tends to distort the film in the remaining region to be sealed. The aperture which is left to be sealed after evacuation and gassing should be small, and well secured in the sealing position, in order to minimize any distortion of the packaging film which might result in a wrinkled seal. However, the reduced size of the aperture and the securing in position thereof tend to slow down the flow of air from the package during evacuation, often resulting in poorly evacuated packages. Also, when replacing the evacuated air with a gas, the gas must be admitted to the evacuated area of the machine at a low enough rate to avoid collapsing the container before sufficient gas has entered the container through its aperture.

It is an object of this invention to provide packaging apparatus, and a method of packaging, that are superior to those available heretofore. Another object of this invention is to provide means which will assure adequate opening of the package aperture during package evacuation so that a maximum amount of air may be re moved from the package in a minimum period of time. Still another object is to provide improved means for evacuating and gassing a package. A further object of this invention is to secure adequate package evacuation with minimum high-vacuum pumping capacity. A still further object is to provide packaging apparatus that is economical to manufacture and operate, reliable in use, and easy to service.

Other objects, aspects and advantages of the invention will in part be pointed out in, and in part apparent from, the following description considered together with the accompanying drawings, in which:

FIGURE 1 is a front elevation of a vacuum-gas packaging machine embodying this invention, with certain portions removed to illustrate internal mechanism;

FIGURE 2 is a right side elevation of the machine in FIGURE 1 with certain portions removed;

FIGURE 3 is a top plan view of the machine in FIG- URE 1 with certain portions removed;

FIGURE 4 is a partial top plan view like FIGURE 3, with additional parts removed to better show the trays in which the packages are made and related structure;

FIGURE 5 is an enlarged sectional view generally taken along the line 55 in FIGURE 4;

FIGURE 6 is an enlarged partial sectional view taken generally along the line 66 in FIGURE 4, and including a right-side elevation of the tray shown in FIGURE 5;

FIGURE 7 is an enlarged sectional view taken generally along the line 77 in FIGURE 4;

FIGURE 8 is an enlarged partial sectional view taken generally along the line 88 in FIGURE 3;

FIGURE 9 is a partial plan view like FIGURE 8, with portions above the tray surface removed;

FIGURE 10 is an enlarged partial sectional view taken generally along the line 1010 in FIGURE 3;

FIGURE 11 is an enlarged partial sectional view taken generally along the line 11--11 in FIGURE 3;

FIGURE 12 illustrates a modified arrangement, viewed as in FIGURE 11;

FIGURE 13 is a rear elevation of the machine shown in FIGURE 1, with certain portions removed;

FIGURE 14 is a timing diagram interrelating the operations performed by the machine;

FIGURE 15 is a modified arrangement showing a tray and related parts as they would appear in cross-section at position 1' in FIGURE 1, taken generally along the.

line 15-45 in FIGURE 3.

Referring first to FIGURES 1 through 4, a rolled up sheet 1 of distendable packaging material is mounted on unwind shaft 2. The sheet 1 is drawn from the roll into the machine by the powered draw-roll unit 3. The sheet 1 then passes under idler roller 4 and guides 82 which apply the sheet 1 to an endless chain of substantially identical packaging trays 5, each mounting a pair of spring-biased clamps 6 which secure the sheet 1 to the surface of the trays. The chain of trays is powered to move intermittently, allowing a dwell time adequate to perform the various operations necessary to producing packages in conjunction with the trays, such as the clamping operation which is performed in the tray which is under guides 82 at the time of clamping. Certain packaging tray positions have been identified in FIGURES 1 and 4 by lower case letters for reference purposes, useful in describing what occurs at these positions.

The clamped sheet 1 is next carried under heater unit 7 (positions b and c) which may be used to raise the temperature of the sheet 1 to a value suitable for differ ential pressure forming, since most such distendable materials are best formed at elevated temperatures. The sheet is then carried under conveyor 8 (position d) where portions of the sheet are formed by vacuum into cavities 9 in the trays, producing a pair of cup-like package parts 10.

In this embodiment of the invention, the articles 11 being packaged are stacks of sliced luncheon meat, which are delivered to the filling region by conveyor 8 where they are manually loaded into cups 10. The sheet 1 with its cups and their fill are then carried to a subsequent position (g) where a packaging head 12 mounting a knife 13 is moved downward, causing the knife 13 to pierce the flat portion of the sheet 1 lying between its cups 10, producing slit 14.

Another coiled sheet 15 of packaging material, heatsealable to sheet 1 but not necessarily distendable to the degree required for sheet 1, is mounted on a second unwind shaft 16. The sheet 15 then is drawn from its roll by the powered draw-roll unit 17. The sheet 15 then passes under idler roller 18 which applies the sheet 15 to the sheet 1, covering its filled cups 10. Sheet 15 is partially sealed to sheet 1 in the subsequent position (/1) when the packaging head 12, mounting partial-heat-sealing bars 19, is moved downward, causing the bars 19 to press the sheets 15 and 1 together against the top surface of the tray positioned thereunder. The bars 19 are arranged in two separate sections, each corresponding to one of the tray cavities 9, which seal the sheets around the periphery of the tray except for a small region between the cavities as indicated by the sealed areas 20 shown shaded in FIGURE 4. The head 12 also mounts a knife 21 which descends with the head into the space between the two trays under the head and completely severs the sheets 15 and 1 transversely between these trays.

The partially-sealed sheets with their enclosed fill are next moved to a position (j) under sealing clamp 22 which is mounted on head 12 with which it descends. This sealing clamp firmly presses the entire periphery of the pair of partially-sealed packages thereunder against the top surface of the tray, and thereby fully hermetically seals the package pair from the atmosphere except for the opening through slit 14. In this position, the package pair is evacuated through the slit and is permanently sealed by heat as will be described.

For this purpose, referring now to FIGURE 11, there is mounted in the central portion of each tray a vertically-shiftable sheet separator 90 which is driven upwards by a pin 91 operated by an actuator 92 supported on the main frame of the machine. Separator 90 is shaped to pass easily through slit 14 without damaging the surrounding portions of sheet 1, and its upper surface smoothly engages sheet 15 to lift this latter sheet away from sheet 1. Thus a communication channel of substantial gas-carrying capacity is formed between slit 14 and the interiors of the two cups on either side of the slit, the separator 90 being fluted on its sides to provide passages for the flow of air out through the slit. Preferably, separator 90 should not be raised so high as to stretch sheet beyond its elastic limit, since the excess material area produced thereby would tend to create wrinkles when sheet 15 is later sealed to sheet 1 in the region of slit 14.

After the sheets 1 and 15 have been separated as described, and while the trays remain in position j, the air from cups 10 is withdrawn through slit 14. To this end there is mounted on actuator 92 a gasket assembly 93 which moves up with separator 90 and engages the underside of the trays to form a continuous conduit running from tubing 94, alongside pin 91 and separator 90, and thence to cups 10 and the fill 11 therein. After this conduit has been established, vacuum is applied to tubing 94 so as to withdraw the air from cups 10 and fill 11.

To hermetically seal the package pair, the head 12 also is provided with a final sealing bar 23 which is moved down onto sheet 15 immediately after separator has been withdrawn from between the sheets at the end of the evacuating operation. This bar 23 presses together the previously unsealed flat central portion of the sheets in the vicinity of slit 14 against the top of the trays, and heat seals these sheet portions together in the area 24, shown shaded in FIGURE 4, thereby isolating slit 14 from the fill and at the same time slightly overlapping the partially-sealed areas 20 to complete the hermetic heatsealing of the two packages.

It should be noted that gasket assembly 93 remains pressed against the trays 5 during this final sealing operation, in order to assure that no air leaks back into the packages. For this purpose, gasket assembly 93 is connected to actuator 92 by a spring 93a which allows the actuator to move the separator 90 into and out of the slit 14 while maintaining the gasket engaged with the trays.

Referring now to FIGURE 4, the package pair 101, completed under sealing clamp 22 and severed by knife 21 from the sheets 15 and 1, is still secured to the tray 5 by clamps 6 in order to hold the package in the tray when the tray subsequently inverts on its way to package removal suction cups 25 (FIGURE 1). Removal cups 25 are mounted on arms 26 which raise these cups into contact with the package pair hanging thereabove, at which time clamps 6 are disengaged. Arms 26 thereupon descend with the package pair 101 and release it to the powered conveyor belts 27. Conveyor belts 27 carry the package pair into engagement with powered shear knives 28 which completely divide the package pair into individual packages 102, generally along the line of the original slit 14. The individual packages remain on the conveyor belts until discharged therefrom as the belts pass over sheaves 29.

Referring now to FIGURE 13, the various operations described above are powered by a gear reduction motor 30 having a power take-off sh aft 30a which mounts sprock et 31, and drives camshaft 32 through chain 33 and sprocket 34. Camshaft 32 (see also FIGURE 2) also mounts Geneva driver 36 and sprocket 37. Sprocket 37 drives idler shaft 45 and camshaft 41 through chain 38 (FIGURE 13) and sprockets 47 and 38a respectively. Shaft 41 also mounts sprocket 39 which drives draw-roll unit 3 through chain 42 and sprocket 40 to which roll 3:: is coupled. Shaft 45 also mounts sprocket 43 which drives draw-roll unit 17 through chain 53 and sprocket 54 (FIGURE 2). Shaft 32 mounts sprocket 46 (see also FIGURE 1) which drives conveyor belts 27 through chain 48 and sprocket 49, mounted on sheave shaft 44. Shaft 44 also mounts sprocket 50 which drives rotary shear knives 28 through chain 51 and sprocket 52.

As shown in FIGURE 2, Geneva driver 36 intermittent ly drives Geneva follower 55 which mounts pinion gear 56. Gear 56 drives the endless chain of packaging trays through idler gear 57 and gear 58 (see also FIGURE l3). Gear 58 is mounted on a shaft carrying sprockets which in turn engage the pair of endless chain 5a on which the trays 5 are mounted, in order to drive the trays intermittently in accordance with the movement of the Geneva follower.

Referring now to FIGURE 3, sprocket 40 drives drawroll unit 3 through clutch 60. The drive ratios in the machine are selected so that draw-rolls 3 feed sheet 1 continuously at a somewhat greater rate than the average outer surface speed of packaging trays 5, which move intermittently. A dancer roll 61 (FIGURE 1) mounted on spring-biased arms 63 pivoted on pins 62 maintains tension in sheet 1 between the packaging trays 5 and draw-rolls 3 until the overfeed from the draw-rolls causes dancer 61 to elevate to its highest position, actuating a limit switch 64 which, through a suitable electrical circuit, releases clutch 60, thereby halting further feeding of sheet 1 by draw-rolls 3. A brake'65 (FIGURE 3) may also be applied to the draw-rolls 3 simultaneously with release of clutch 60 to substantially eliminate any overfeed due to the momentum of the rolls.

Indexing of the trays will cause the sheet 1 to depress the dancer roll 61, releasing arms 63 from engagement with switch 64, and releasing in turn brake 65 and reengaging clutch 60 to resume feeding of sheet 1.

The draw-roll unit 17 in FIGURES 1 and 2 operates to feed the sheet in identical fashion to the operation of draw-roll unit 3 as described immediately above.

The heater 7 is composed of a plurality of tubular electrical resistance heaters 76. Conventional controls (not shown) provide for their operation at desired temperatures from ambient to approximately 1500 F., within which range radiation i produced of wave-lengths well suited to the heating of various distendable packaging materials. The heater 7 mounts rollers 77 (see also FIGURE 3) which roll in tracks 78, allowing the heater 7 to be retracted from the area over the sheet 1 when the machine is stopped, to prevent overheating of the sheet 1 and trays 5. The heater is driven into operative position by a pneumatic cylinder and piston unit 79 operated by a solenoid valve 103 controlled by a start-stop switch 104-. When the heater has reached its operative position as shown in FIGURE 3, it closes a switch 105 to complete a circuit supplying current to the motor 30. When start-stop switch 104 is opened, conventional poweroperated means such as a pneumatic unit or spring means (not shown) operate to retract heater 7, thereby opening motor switch 105 and stopping the machine.

The conveyor 8 may be powered independently of the machine or through conventional power transmission elements (not shown) from camshaft 3-2. Powering the conveyor from the machine has the advantage of maintaining its speed at a fixed ratio to the average speed of the trays 5. Indicia 80 may be imposed on conveyor 8 to direct the loading of the articles 11 on the conveyor so that a pair of the articles will be in a convenient position for manual transfer into the cups 10 every time a pair of the cups emerges from under the conveyor.

Liquids and many articles such as nuts, powders, granulated materials and the like may automatically be metered into the cups 10 by means of conventional equipment familiar to those versed in the art. Other articles such as frankfurters might require special feeding devices for automatic handling.

Although the shear knives 28 are designed to completely sever the package pairs advanced therethrough by the conveyor belts 27, these knives may be serrated or otherwise fashioned to partially sever the package pairs, since it may sometimes be desirable to market paired packages which the purchaser may tear apart manually, without damage to their hermetic seals. The shear knives 28 may be omitted entirely should uncut paired packages be desired.

FIGURE 14 shows the time relationships between the various operations previously described. In order to simplify understanding of the machine timing, all displacements in FIGURE 14 have been scaled to be schematically portrayed as equal, and straight diagonal lines have been used to connect the displacement positions. All of the motions shown (with the exception of that of the trays which is produced by the Geneva mechanism previously described) are produced by linkages which may include bell-cranks mounting follower rollers, actuated by suitably designed cams mounted on camshafts 3'2 and 41. In the interest of more clearly illustrating the invention, these cams and linkages have not been shown. They are of conventional design and no invention is herein claimed regarding them. Cam-shafts 32 and 41 operate at the same speed, equal to one revolution per machine cycle (i.e. one advance step of the trays), or 360 as illustrated in FIGURE 14.

Upper case letters have been used in FIGURE 14 to identify each of the schematic timing curves:

Curve A shows the indexing motion of the packaging trays 5; inspection of the other curves will show that trays 5 are not engaged by the other functions illustrated while trays 5 are in motion.

Curve B illustrates the action of clamps 6 of a tray in position a. FIGURE 5 shows the clamps prior to being opened by actuators 81, FIGURE 6 shows one of the clamps open to receive the sheet 1, and FIGURE 7 shows the clamps pressed down on the sheet, the sheet 1 having been sprung thereunder by the action of roller 4 and guides 82. Guides 82 are rigidly mounted to machine frames 83 by means not shown. The packaging trays 5 are slidably mounted by nylon blocks 107 in tracks 84, also rigidly mounted to frames 83, an upper and lower pair of the tracks defining the path of the trays in its horizontal reaches and providing the trays with support. Actuators 81 are moved in unison, being driven from camshaft 41.

Curve C illustrates the action of cup-forming vacuumgasket 85, shown in FIGURE 7 engaged with a packaging tray in position a. Gasket 85 is mounted on a vacuum conduit portion of actuator 86 which is driven from camshaft 41. Gasket 85 engages the bottom surface of the central portion of the tray, and establishes a communication channel with the cavities 9 through passageways 108 (see also FIGURES 8 and 9) formed in each tray.

Curve D illustrates the action of a poppet valve (not shown) driven from camshaft 32, which connects a vacuum source to the conduit portion of actuator 86 and causes air to be withdrawn through gasket 85 from under sheet 1 to form the cups 10 from the sheet in position d by the force of atmospheric pressure. The depths of cups 10 may be controlled by selection of interchangeable filler blocks 87 of suitable thickness. It is understood that mechanical means may be substituted for or used in conjunction with vacuum for the forming of cups 10; fluid pressure above atmospheric may also be employed in forming the cups.

Additional gaskets 85a and 85b, and corresponding air conduits, are mounted on actuator 86 to remove air from under cups in subsequent positions e and f. The passage through gasket 85a is smaller than the passage through gasket 85, and the passage through gasket 85b is smaller than the passage through gasket 85a. In the timing of this cup-forming operation, vacuum is applied to gaskets 85a and 85b slightly before vacuum is applied to gasket 85. This arrangement prevents sheet 1 from flowing from positions 2 and 7 toward position d due to the forming forces applied at the latter position. It has been found that employing such graduated vacuum levels in each of said positions, as by means of the differentsized passages, holds the sheet better than when the vacuum level is the same throughout.

Curve E shows the motion of packaging head 12. This motion, being small, is vertical for practical purposes since head 12 (FIGURES 3 and 13) is mounted on long arms rotating about pivots 88. Head 12 mounts the knife 13 whose motion also follows curve B. Knife 13 is shown in FIGURE 8 engaged with a packaging tray in position g; also partially shown are previously inserted stacks of luncheon meat 11 resting in the cups 10. Curve E also illustrates the motion of partial-sealing bars 19 mounted on head 12, and shown in FIGURE 10 engaged with a tray in position h. Support bars 89 mounted to frames 83 (by structure not shown) relieve the tracks 84 from resisting all of the force applied to the tray by the sealing bars 19.

Curve E also shows the motion of knife 21 mounted on packaging head 12. Knife 21 may be omitted, or constructed to perforate or partially sever the sheets 1 and 15 between successive package pairs rather than sever them completely, should it be desired to deliver packages in continuous strips, perhaps to a trimming device as in the case of other than rectangularly-shaped packages. In some applications, it is preferable to pro? vide knife 21 between positions and k, so that the package is severed after it has been evacuated and sealed. Such a modified arrangement is shown in FIGURE 15. Curve E will also illustrate the motion of sealing clamp 22 which is mounted on head 12 and shown in FIGURE 11 engaged with a packaging tray in position j. Support bars 89 also extend under the tray in position j to assist tracks 84 to resist the force applied by clamp 22.

Curve F illustrates the action of sheet separator 90 of a tray in position j. FIGURES 8 and 9 show separator 90 in its retracted position, and FIGURE 11 shows the separator protruding from its tray into operative position as discussed above.

Curve G illustrates the action of a poppet valve (not shown) driven from camshaft 32, which connects a vacuum source with tubing 94, causing air to be withdrawn from cups 10 when the tray is in position j.

Curve H shows the motion of final sealing bar 23, which completes the seal already made in position It, hermetically sealing the fill 11 in the cups 10. Bar 23 is driven from camshaft 41 through an actuator 23a.

Curve I illustrates the action of a poppet valve (not shown) driven from camshaft 32 and connecting the atmosphere with tubing 94, which readmits air to the tray in position 1 after the cups have been completely sealed.

When it is desired to produce hermetically-sealed packages from which the air has first been evacuated and then replaced with a gas, the package evacuation valve is closed somewhat earlier than illustrated in curve G. A gas valve (not shown) operated from camshaft 32, and connecting a gas supply with tubing 94, then feeds gas into and under the cups 10 after evacuation ceases, closing before the final seal is made by the bar 23.

While the package pair is being evacuated, it is desirable to apply vacuum to the spaces 100 beneath sealing clamp 22 to prevent the pressure of atmospheric air from exerting any substantial force on the upper surface of sheet 15 which otherwise would tend to drive the sheet down into the packaging tray 5 and possibly rupture the sheet or draw the rim of the package pair from under clamp 22. For this purpose, in one embodiment of the invention the tubing 94 is connected (by conventional means, not shown) directly to a tubing 95 which communicates with spaces 100, in order to assure that the pressure in spaces 100 will be comparable to the pressure within the cups 10.

For some applications, it may be desirable to evacuate the clamp spaces 100 by means of a vacuum source separate from the vacuum source connected to tubing 94. This is illustrated by curves K and L in FIGURE 14. Curve K shows the action of a clamp evacuation valve connected between such a separate vacuum source and tubing 95, and operated from camshaft 32. Curve L shows the action of a clamp vent valve connected between atmosphere and the tubing 95, and also operated by camshaft 32. As can be seen from FIGURE 14, the clamp evacuation valve (curve K) opens and closes at substantially the same time as the package evacuation valve (curve G), and the clamp vent valve opens and closes at substantially the same time as the package vent valve (curve J). Since it is not necessary to evacuate spaces 100 to the same extent as cups 10, the separate vacuum source for spaces 100 is a relatively inexpensive type of lower capacity than the main vacuum source for tubing 94. Moreover, if the package is to be filled with gas subsequent to its evacuation, this modified arrangement affords a saving in required gas volume since spaces 100 will not be filled with gas. It should also be noted that this separate low-capacity vacuum source may additionally be used for forming sheet 1 into cups 10, holding the cups in position in the trays 5, and removing the package pairs from the trays.

The sequence shown in FIGURE 14 for the steps involved in evacuation of a package pair in position after the sealing clamp 22 engages a tray 5, shows the sheet separator (curve F) protruding first, then the package evacuation valve (curve G) opens, approximately at the same time the clamp evacuation valve (curve K) opens.

Curve M illustrates the action of clamps 6 of a tray in position I. The completed package pair is released from the tray by this action of the clamps, which are in turn controlled by actuators 96. Actuators 96 move in unison, being driven from camshaft 41. Actuators 96 and 81 are substantially identical.

Curve N illustrates the action of package removal cups 25. Cups 25 are mounted on arms 26 which are driven from camshaft 32. The motion of cups 25 is coordinated with the action of clamps 6 in position I so that cups 25 will be engaged with the package pair in the packaging tray at the time the clamps 6 release the packages.

Curve 0 illustrates the action of a conventional three way valve driven from camshaft 32, and which connects a vacuum source to the cups 25 when they are engaged with the package pair in position I, retaining the packages in engagement with the cups until the package pair is lowered to the upper surface of conveyor belts 27. At this latter time, the valve is operated to shut off the vacuum and vent the cups 25 to the atmosphere, thereby releasing the package pair to the conveyor belts.

At times during operation of the machine, it becomes necessary to service the sealing bars and knives carrying the packaging head. To more readily accommodate such servicing, head 12 (referring now to FIGURES l, 2 and 13) is mounted on arms 12a by means of a pivot bar 109 and a release bar 110, both extending transversely with respect to arms 12a. When it is necessary to obtain access to the various parts carried by head 12, the release bar 110 is pulled out, and the head is tipped back to the position shown in broken outline in FIGURE 13. This arrangement is particularly advantageous because the head 12 may easily be shifted to its servicing position by the machine operator, without requiring any complex disassembly operations.

Although packages rectangular in their plan view have been illustrated for stacked luncheon meat, wedges, ovals, circles or other plan view shapes better suited to various other articles may be produced on this machine by constructing the cavities 9 in the trays 5 to the desired shape. The bottoms 87 of the trays may also be contoured in elevation, if desired. In order to produce minimal flanges on shaped packages, the partial sealing bars 19 may be constructed to produce seals closely bounding the shaped cavity edges; the flanges external to the package seals may then be trimmed away in a subsequent operation.

This invention lends itself particularly well to high production, since packaging trays may be made with a multiplicity of cavities 9 to produce two or more package pairs in a transverse direction in each tray and the machine widened for accommodating these trays, all motions shown in FIGURE 14 remaining unchanged.

If it is desired to package elongated articles such as certain unsliced sausage products without changing the spacing of machine frames 83, such articles 11a may be packaged singly as shown in FIGURE 12 instead of paired as hereinbefore described for sliced luncheon meat. In this modification, the tray has only a single cavity, and the packaging machine is arranged in such a manner that the sheets 1 and 15 are heat-sealed around the entire eriphery of the single cup 10a at position It. In position g, the knife 13 (located off-center in this modification) slits the sheet 1 in the left-hand side edge of cup 10a. As shown in FIGURE 12, sheet separator 90 (also located off-center) passes through this slit and raises the upper sheet 15 to provide a gas-carrying channel through which the package is evacuated in the manner illustrated and described with reference to FIGURE 11. As before, sealing bar 23 descends after this evacuation to seal the areas around the slit. Although the production rate for singly produced packages is only half that of packages which have been paired, lower relative machine cost may make singly produced packages more desirable for larger articles. It may now be observed that the basic machine hereinbefore described may readily be adapted to a variety of package sizes and shapes without changing frame size or spacing, drives, cams, linkages, etc. Transverse relocation of standard actuators, plus suitably constructed partial sealing units and sealing clamp, to cooperate with suitable packaging trays, will adapt the machine to many different packages.

Although several specific embodiments of the invention have been set forth in detail, it is desired to emphasize that these are not intended to be exhaustive or necessarily limitative; on the contrary, the showing herein is for the purpose of illustrating the invention and thus to enable others skilled in the art to adapt the invention in such ways as meet the requirements of particular applications, it being understood that various modifications may be made Without departing from the scope of the invention as limited by the prior art.

I claim:

1. The method of evacuating a container made from two sheet portions superimposed upon one another and sealed around their peripheries, one of said sheet portions being provided with an opening through which the evacuation is effected; said method comprising the steps of: moving the entire imperforate sheet portion lying within the sealed periphery thereof in a direction away from said opening while maintaining the perforate sheet portion from movement in said direction, so as to form a communication channel of substantial capacity between said opening and the interior of said container Without excessive stretching of the sheet material, evacuating said container through said opening while holding said imperforate sheet portion away fro-m the opening, thereby to positively maintain said communication channel during the evacuation of said container, and sealing together the opposing surfaces of said sheet portions in the region of said opening to hermetically isolate said opening from the interior of said container.

2. The method as claimed in claim 1, including the step of varying the pressure on the outside of said one sheet portion, over the entire area thereof lying within said sealed periphery, in accordance with the changes in pressure inside said container during evacuation thereof.

3. The method as claimed in claim 1, including the step of maintaining the pressure on the entire outside of said container at substantially the same level as the pressure inside the container during evacuation thereof.

4. The method as claimed in claim 1, including the step of maintaining the pressure on the outside of said imperforate sheet portion, over the entire area thereof lying within said sealed periphery, at least approximately equal to the pressure inside the container during evacuation thereof.

5. The method as claimed in claim 1, including the step of maintaining the pressure on the outside of said imperforate sheet portion, over the entire area thereof lying within said sealed periphery, at a level slightly above the pressure in the container during evacuation thereof.

6. The method of evacuating a container made from two sheet portions superimposed upon one another and sealed around their peripheries, one of said sheet portions being provided with an opening through which the evacuation is effected; said method comprising the steps of: holding said two sheet portions in an initial position with said opening closely adjacent the imperforate sheet portion, inserting an element through said opening to push the imperforate sheet portion from said initial position to a distended position spaced from said opening while maintaining the perforate sheet portion in said initial position, thereby to form a communication channel of 1G substantial capacity between said opening and the interior of said container, evacuating said container through said opening, and sealing together the opposing surfaces of said sheet portions in the region of said opening to hermetically isolate said opening from the interior of said container.

7. The method of vacuum packaging which includes supplying a first layer of heat-stretch material to a series of cavities and heating the film to increase its stretchability, forming said material into said cavities to provide corresponding cups, depositing in said cups the articles to be packaged, creating an opening in the flange portion of said formed cups intermediate two of said cups, applying a second layer of material to said first layer to form packages, sealing said second layer to the first layer substantially around the periphery of the cups adjacent said opening while leaving said layers unsealed in the region of said opening, pushing said second layer away from said first layer, evacuating the packages through said opening, sealing off said opening in a region thereof between the opening and the interior of the corresponding packages, and severing the packages exterior to the seals thus formed.

8. The method of making an evacuated package from two layers of packaging material, comprising the steps of providing an opening in one of said layers, sealing together said layers around a peripheral region surrounding said opening and immediately adjacent thereto, stretching the imperforate layer to move it in a direction away from the other layer in the region of said opening, evacuating said package through said opening while holding said imperforate layer away from said other layer, and sealing said layers together in the region of said opening to complete the hermetic seal of said package.

9. The method of making an evacuated package comprising the steps of supplying a first layer of material to a package-carrying means having at least one cavity therein, stretching said material into said cavity to form a cup, slitting said material to provide an opening adjacent a peripheral margin of said cup, supplying a second layer of material over said first layer of material, heat-sealing said two layers together at least substantially around a peripheral region of said package-carrying means to form a container, clamping said container entirely around said peripheral region to assure that the interior of said container is hermetically sealed from atmosphere except for the passage through said opening, moving an element through said opening to engage the inside surface of said second layer and push said second layer away from said first layer to provide a communication channel from said opening to the interior of said container, applying vacuum to said opening to evacuate said container, removing said element from said opening, heat-sealing said first and second layers together in the region of said opening to form a complete heat-sealing of said container from outside atmosphere, and releasing the clamping around said peripheral region of said packagecarrying means.

10. Apparatus for evacuating a container having two opposed sides with one of said sides including an opening therein, said apparatus comprising, in combination, holding means for supporting said container, evacuation means positioned adjacent the side of said container having said opening and including means to provide a conduit through said opening to evacuate said container, pressure-compensating means engageable with the other side of said container to seal the entire area of said other side from atmosphere, and vacuum means connected to said pressure-compensating means to reduce the pressure applied to said other side of said container during the evacuation of said container.

11. Apparatus as claimed in claim 10, wherein said vacuum means comprises means in communication with said evacuation means.

12. Apparatus for making packages comprising, in

combination, a series of container-carrying devices, support means mounting said devices for movement, drive means for moving said devices, a start-stop switch for controlling said drive means, sheet supplying means adjacent said devices for feeding sheet material onto said devices, heater means normally located in a position over said sheet material to raise the temperature thereof sufficiently to permit ready stretching of said sheet material, mounting means for said heater means arranged to accommodate movement of said heater means from said position over said sheet material into a second position remote from said sheet material, operating means for moving said heater means between said positions; said operating means being controlled by said start-stop switch to position said heater means over said sheet material when said start-stop switch is actuated to energize said drive means, and to position said heater means remote from said sheet material when said start-stop switch is actuated to deenergize said drive means; and container-forming means for stretching the heated sheet material onto said container-carrying devices.

13. Apparatus as claimed in claim 12, including means under the control of said heater means to energize said drive means when said operating means has moved said heater means into position over said sheet material.

14. The method of making an evacuated container comprising the steps of: securing together a pair of opposed sheets of flexible material to provide a container having a surrounding peripheral flange, said sheets being positioned close together in one region thereof which lies generally in the area defined by said peripheral flange, providing one of said sheets in said region with an opening through which the evacuation is effected; pushing the imperforate sheet away from said one sheet by applying stretching force thereto to form a communication channel of substantial capacity between said opening and the interior of said container, evacuating said container through said opening while holding said impcrforate sheet away from said one sheet, and sealing together the opposing surfaces of said sheets in the region of said opening to hermetically isolate said opening from the interior of said container.

15. The method of making an evacuated container comprising the steps of: forming a first flexible sheet with at least one cup-like bulge to receive a product to be packaged, securing a second sheet to said first sheet along peripheral edges thereof to form a peripheral flange, providing an opening in said first sheet in a region thereof lying generally in the interior area defined by said flange, separating said second sheet from said first sheet by applying a stretching force to all parts of said second sheet within said peripheral flange to establish a communication channel of substantial capacity between said opening and the interior of said container, evacuating said container through said opening while holding said second sheet away from said first sheet, and sealing said sheets together in the region of said opening to hermetically isolate said opening from the interior of said container.

16. The method of forming an evacuated package comprising a container made from two superposed sheet portions one of which is provided with an evacuation opening, said method including the steps of: supporting the perforate sheet in the region of said opening, inserting a member through said opening to stretch the imperforate sheet away from the supported perforate sheet, evacuating the container through the opening, and pressing the imperforate sheet against the supported perforate sheet in the region of said opening to seal the two sheets together in said region.

17. The method of claim 16, including the step of heating said two sheets in the region of said opening while said imperforate sheet is being pressed against said supported perforate sheet.

18. Apparatus for forming an evacuated package comprising a container-carrying device adapted to receive a container including two superposed sheet portions one of which is provided with an opening therein, a support surface forming part of said container-carrying device arranged to support said one sheet portion in the region of said opening, said support surface being provided with an aperture opposite said opening, a sheet separator mounted for movement within said aperture and through said opening to push the imperforate sheet portion away from said one sheet by applying a stretching force thereto, means for reciprocating said sheet separator during an evacuation operation, and sealing means movable to force said two sheet portions against said support surface after evacuation of said container, to press and seal together said two sheet portions in the region of said opening.

19. The method of vacuum packaging which includes supplying a first layer of packaging material to a series of cup-like cavities and stretching the material into the cavities to form a corresponding series of cups, depositing in the cups articles to be packaged, creating an opening in the flange portion interconnecting at least two of the cups and applying a second layer of packaging material over said first layer to form packages, sealing said second layer to said first layer around the periphery of at least one cup adjacent said opening but leaving a communication channel connecting said opening with the interior of said one cup, pushing the entire portion of said second layer of material which is located within said periphery away from said first layer of material so as to provide said communication channel with substantial gas flow capacity without excessive stretching, evacuating the package formed by said one cup through said opening while holding said entire portion of said second layer of material away from said first layer of material, and sealing off said opening.

20. The method of vacuum packaging which includes supplying a first layer of heat-stretch material to a series of cavities and heating the material to make it stretchable, stretching the material into the cavities to form corresponding cups, inserting in the cups thus formed articles to be packaged, punching an opening in a marginal portion of said material, applying a second layer of material to form a package, sealing said second layer to the first layer around its periphery but exterior to said marginal opening, applying stretching force to all parts of said second layer located within said periphery to move said second layer away from said first layer to form a communication channel of large capacity without excessive stretching of said material, evacuating the package through said opening, and sealing off said opening.

21. Packaging apparatus for evacuating a container of the type including a pair of opposed surfaces one of which is provided with an opening therein, said apparatus comprising, in combination, holding means for supporting said container firmly in position; a sheet separator positioned adjacent said holding means, said separator being mounted for movement relative to said holding means; means operable duringa packaging operation for moving said sheet separator with respect to said holding means and through said opening to engage the opposite surface of said container and stretch it away from said one container surface; and evacuating means communicating with the outside of said one container surface around said opening to withdraw air from said container through said opening.

22. Apparatus as claimed in claim 21, wherein said holding means comprises a tray having clamp means for engaging said container in the peripheral edges thereof.

23. Apparatus as claimed in claim 21, wherein said sheet separator consists of a thin barlike element extending generally parallel to the plane of said opposed surfaces.

24. Apparatus as claimed in claim 23, wherein said 13 element is fluted along the side thereof to form passages for the flow of gas past said element.

25. Apparatus as claimed in claim 21, wherein said holding means comprises a tray having two cavities positioned side-by-side, said sheet separator being mounted in said tray between said cavities.

26. Apparatus as claimed in claim 22, wherein said separator is formed with an internal conduit extending therethrough to an aperture in a region adjacent the end of said separator that engages said opposite surface, whereby said separator also serves to admit gas to said container.

27. Apparatus as claimed in claim 26, wherein said separator comprises a bar-like part adapted to fit through a slit-shaped opening in the container, said conduit aperture being located on one side of said separator part.

28. The method of making evacuated packages comprising the steps of forming a sheet of packaging material into a pair of cup-shaped pocket parts positioned side-byside and joined together by a flange portion, providing an opening in said flange portion, sealing to said pair of pocket parts a second sheet of packaging material to form a pair of containers, holding said second sheet in such a manner that any part thereof Within the sealed region is free to be moved away from said first sheet, pushing said second sheet in a region thereof adjacent said opening so that the entire sealed portion of said second sheet is stretched away from the first sheet, thereby producing an evacuation channel of substantial capacity without excessive stretching, evacuating said containers through said opening, and sealing said two sheets together in the region of said opening.

29. The method of making evacuated packages comprising the steps of forming a sheet of packaging material into two cup-shaped pocket parts positioned side-by-side and joined together by a flange, forming an opening in said flange, positioning a second sheet of packaging material over said pocket parts to define a pair of containers, forming a preliminary seal between said two sheets around the periphery of said two containers but not in the region of said opening, pushing the entire extent of said second sheet located within said preliminary seal away from the first sheet, evacuating said two containers through said opening, and forming a second seal between said two sheets in the region of said opening.

30. The method of claim 29, wherein said second seal overlaps said preliminary seal to assure a complete hermetic sealing of both of said containers individually.

31. The method of evacuating a container made from two sheet portions superimposed upon one another and sealed around their peripheries, one of said sheet portions being provided With an opening through which the evacuation is to be eifected, said opening normally lying close to the other sheet portion, comprising the steps of: bolding said imperforate sheet portion in its normal position lying within the area defined by said peripheries and aligned therewith, stretching said imperforate sheet portion from said normal position and in a direction away from the perforate sheet portion to a distended position spaced from the perforate sheet portion, and evacuating said container through said opening while holding said imperforate sheet portion away from the opening, thereby to maintain an evacuation channel of substantial size during the evacuation operation.

32. The method of evacuating a container made from two sheet portions superimposed upon one another and sealed around their peripheries, one of said sheet portions being provided with an opening through which the evacuation is to be effected, said opening normally lying close to the other sheet portion, comprising the steps of: holding the imperforate sheet portion initially in its normal essentially unstretched position aligned with the sealed peripheries thereof, pushing said imperforate sheet portion in a region thereof opposite the opening in the other sheet to move the imperforate sheet portion away from said normal position to a position spaced from said other sheet by applying a stretching force to substantially all parts of said imperforate sheet portion lying Within said peripheral edges, thereby to form an evacuation channel of substantial size without excessive stretching of any localized region of said imperforate sheet portion, and evacuating said container through said opening.

33. Packaging apparatus for evacuating a container of the type including a pair of normally-adjacent opposed surfaces one of which is provided with an opening through which the container is to be evacuated, said apparatus comprising, in combination, holding means for supporting the container in position, means for evacuating said container, a sheet separator positioned adjacent said holding means and mounted for movement with respect thereto, means for moving said sheet separator through said opening to engage the opposite surface of said container and stretch it away from said one surface to provide between said surfaces a communication channel having substantial gas flow capacity without excessive stretching of the container material, said sheet separator further being formed with an internal conduit extending through said separator to an aperture adjacent the end thereof that engages said opposite surface to define a passageway leading from outside said container through said separator to said communication channel between said surfaces.

References Cited in the file of this patent UNITED STATES PATENTS 2,116,995 Bickford May 10, 1938 2,387,812 Sonneborn et a1 Oct. 30, 1945 2,432,373 Bleam et a1 Dec. 9, 1947 2,565,444 Waters Aug. 21, 1951 2,712,208 Campbell July 5, 1955 2,753,671 De Puy et al July 10, 1956 2,888,787 Cloud June 2, 1959 2,888,788 Gebhardt June 2, 1959 2,892,294 La Branche June 30, 1959 2,935,828 Mahaify et al May 10, 1960 

